body {
  font-family: "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background-color: #f8f9fb;
  color: #1e1e1e;
  margin: 2rem auto;
  padding: 0 1.5rem;
  max-width: 900px;
  line-height: 1.6;
}

h1, h2, h3 {
  color: #004080;
}

h1 {
  border-bottom: 3px solid #00aaff;
  padding-bottom: 0.4rem;
}

nav {
  margin-bottom: 2rem;
  font-size: 1rem;
}

nav a {
  text-decoration: none;
  color: #007acc;
  margin-right: 0.75rem;
}

nav a:hover {
  text-decoration: underline;
  color: #005999;
}

table {
  width: 100%;
  border-collapse: collapse;
  margin: 1rem 0;
  background-color: #fff;
}

th,
td {
  border: 1px solid #ccc;
  padding: 0.6rem;
  text-align: left;
}

th {
  background-color: #e8f4ff;
}

code {
  background: #eef;
  padding: 2px 4px;
  border-radius: 3px;
  font-family: monospace;
}

hr {
  margin: 2rem 0;
  border: none;
  border-top: 2px solid #e0e0e0;
}

.emoji {
  font-size: 1.3rem;
}

.citation-box {
  background-color: #e8f4ff;
  border-left: 5px solid #00aaff;
  padding: 1rem 1.25rem;
  border-radius: 8px;
  margin-top: 1rem;
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.08);
}

.citation-box strong {
  color: #003366;
}

.citation-box a {
  color: #006bb3;
  text-decoration: none;
}

.citation-box a:hover {
  text-decoration: underline;
}

details {
  margin-top: 0.75rem;
}

summary {
  cursor: pointer;
  color: #004080;
  font-weight: 600;
}

pre {
  background-color: #f4f7fb;
  padding: 1em;
  border-radius: 6px;
  overflow-x: auto;
  font-size: 0.9rem;
}

/* Scoring/Walkthrough helpers */
.explanation {
  margin-bottom: 2em;
}

.math-block {
  margin: 1em 0;
}

.math-fallback {
  display: none;
  background: #fff;
  border: 1px solid #ccc;
}

.no-mathml math {
  display: none;
}

.no-mathml .math-fallback {
  display: block;
}

.walkthrough {
  margin: 2em 0;
  background: #f9f9f9;
  padding: 1em;
  border-radius: 8px;
  border-left: 4px solid #6a8caf;
}

.walk-step {
  display: none;
  transition: all 0.3s ease-in-out;
}

.walk-step.active {
  display: block;
}

.walk-controls {
  text-align: center;
  margin-top: 1em;
}

.walk-controls button {
  padding: 0.5em 1em;
  margin: 0 1em;
  font-size: 1em;
  cursor: pointer;
  background-color: #6a8caf;
  color: white;
  border: none;
  border-radius: 4px;
}

.walk-controls button:disabled {
  background-color: #ccc;
  cursor: not-allowed;
}